Subarachnoid haemorrhage Flashcards
What is a subarachnoid haemorrhage?
This is a haemorrhage underneath the arachnoid mater - between arachnoid mater and pia mater
What is the typical presentation of subarachnoid haemorrhage? 8 features
- acute severe headache - like blow to back of head with baseball bat
- occipital headache
- neck stiffness, photophobia (meningism)
- pain maximal at headache onset
- seizures
- neurological deficits
- decreased consciousness/coma
- death
What are 4 risk factors for haemorrhagic stroke?
- Age
- Hypertension
- Arteriovenous malformation
- Anticoagulation therapy
What are 4 features that may help differentiate haemorrhagic from ischaemic stroke, that are more common in haemorrhagic?
- Decreased level of consciousness (up to 50% of patients)
- Headache
- Nausea and vomiting
- Seizures (in up to 25%)
What is the most common cause of subarachnoid haemorrhage?
head injury - truamatic SAH
What are 2 broad types of subarachnoid haemorrhage?
- Traumatic SAH (most common)
- Spontaneous SAH
What are 6 causes of spontaneous SAH?
- Intracranial aneurysm (saccular ‘berry’ aneurysms)
- Arteriovenous malformation
- Pituitary apoplexy (bleeding into it/impaired blood supply)
- Arterial dissection
- Mycotic (infective) aneurysms
- Perimesencephalic (idiopathic venous bleed)
What is the commonest cause of spontaneous SAH?
intracranial aneurysm - saccular aneurysms (85%)
What are 3 examples of conditions associated with berry aneurysms?
- Adult polycystic kidney disease
- Ehlers Danlos syndrome
- Coarctation of the aorta
What ECG changes may sometimes be seen in sabarachnoid haemorrhage?
ST elevation
What is the first line investigation used to diagnose subarachnoid haemorrhage and what will it show?
CT: acute blood (hyperdense/bright on CT) distributed in basal cisterns, sulci and in severe cases the ventricular system
What are 3 places where hyperdense/bright blood may be seen on CT in SAH?
- Basal cisterns
- Sulci
- Ventricular system (severe cases)
In what proportion of cases of SAH is CT negative?
7%
If CT is negative for SAH what is the next investigation which can confirm if SAH is present?
Lumpar puncture
When must lumbar puncture be performed when being used to help confirm SAH?
at least 12 hours following onset of symptoms to allow development of xanthochromia (result of red blood cell breakdown)